The invention pertains to a drill steel and chuck assembly, as well as associated adapters, that are for use in drilling holes in the roof of an underground mine tunnel.
The expansion of an underground mine (e.g.a coal mine) requires digging a tunnel which initially has an unsupported roof. To stabilize and support the roof a roof bolt must be inserted into the roof to provide support. The operator must first drill holes in the roof through the use of a rotatable cutting bit or roof drill bit. A roof bolt is then inserted into each one of the holes.
The roof drill bit is typically connected to the machine that rotates the bit by a drill steel. The drill steel is typically a hexagonally-shaped elongate rod. The roof drill bit connects to the drill steel at the distal (or upper) end thereof. The drill steel connects at the other end thereof to the machine that powers the roof drill bit. Sometimes these connections are made via chucks or some type of coupling.
In one instance, the drill steel (hexagonally-shaped) is inserted into a chuck with a hexagonally-shaped bore so as to provide torque to the roof drill bit, which is connected to the drill steel, for drilling the bolt holes. Upon completion of drilling the bolt hole using the above drill bit-chuck-drill steel assembly, the chuck is lowered from the ceiling and the drill bit and the drill steel normally follow under the influence of gravity. However, on occasion, the drill steel snags on the surface (of the earth strata) defining the bolt hole and does not fall out of the bolt hole under its own weight. The consequence of this occurrence is that the operator must manually remove the drill steel (and the roof drill bit) from the bolt hole. Because there is an increase in the automation of the bolt hole drilling operation, the operator is not always readily available to manually remove the drill steel from the bolt hole.
There are earlier lockable designs for a roof drilling system such as those disclosed in U.S. Pat. No. 4,773,490 to McSweeney et al., U.S. Pat. No. 4,702,290 to McSweeney et al., U.S. Pat. No. 4,632,195 to Emmerich et al., and U.S. Pat. No. 4,226,290 to McSweeney. These designs are, however, somewhat complex so that they are subject to malfunction and failure, especially in view of the severity of the operating environment.
It would be desirable to provide for a drill steel-chuck assembly (preferably of a simple design) in which these components are positively locked (or connected) together so that the drill steel can still be removed from the bolt hole even if it snags on the earth strata defining the bolt hole. It is also apparent that it would be desirable if such a drill steel-chuck assembly would be easily releasable (and connectable). It is further apparent that it would be desirable if such a drill steel-chuck assembly would provide for a positive driving connection between these components.
It is additionally apparent that it would be desirable if such a drill steel-chuck assembly would be compatible with existing equipment so that, for example, a drill steel of the invention would be compatible with an earlier chuck. Another example would be the use of an adapter to convert conventional straight drill steels to be suitable for use with the above-mentioned drill steels and/or chucks. By providing such an adapter, longer lengths of conventional straight drill steel could be cut to length and used with the above-mentioned drill steels and/or chucks. These features would permit an operator to have a mixed inventory of drill steels and chucks of the invention along with earlier drill steels and chucks.
In one form thereof, the invention is a drill steel-chuck assembly comprising a drill steel having a plurality of faces and opposite ends. The drill steel has one portion adjacent one of the opposite ends thereof and a mediate portion spaced apart from the one portion. The drill steel has one transition portion between the one portion and the mediate portion so as to join the one portion and the mediate portion. The one portion of the drill steel presents a first orientation of the faces. The mediate portion of the drill steel presents a second orientation of the faces. The one transition portion of the drill steel presents a twisted orientation of the faces comprising a generally constant twist of the faces from the first orientation of the one portion to the second orientation of the mediate portion. There is a chuck for attachment to the drill steel through engagement with the transition portion of the drill steel.
In another form thereof, the invention is a cutting bit assembly comprising a cutting bit and a drill steel which has a plurality of faces. The drill steel also has opposite ends. The cutting bit is in operative connection to the drill steel at one end thereof. The drill steel has one portion adjacent one of the opposite ends thereof and a mediate portion spaced apart from the one portion. The drill steel has one transition portion between the one portion and the mediate portion so as to join the one portion and the mediate portion. The one portion of the drill steel presents one orientation of the faces, and the mediate portion of the drill steel presents another orientation of the faces. The one transition portion of the drill steel presents a twisted orientation of the faces comprising a generally constant twist of the faces from the one orientation of the one portion to the other orientation of the mediate portion. A chuck attaches to the drill steel through engagement with the transition portion of the drill steel.
In still another form thereof, the invention is a drill steel-chuck assembly comprising a drill which has opposite ends wherein the drill steel presents a twisted portion adjacent to one of the ends. There is a chuck wherein the chuck contains a central bore which presents a twisted axial surface which corresponds to the twist of the twisted portion of the drill steel. The twisted portion of the drill steel is received in the central bore of the chuck so that the twisted portion of the drill steel contacts the twisted axial surface so as to form a secure attachment between the drill steel and the chuck.
In yet another form thereof, the invention is an adapter for use in connecting a pair of drill steels wherein the adjacent ends of the drill steels present a bore with a twisted portion. The adapter comprises an elongate body which has an upper end and a lower end. The elongate body presents a twisted upper portion adjacent to the upper end thereof and a lower twisted portion adjacent to the lower end thereof. The angle of twist of the upper twisted portion corresponds to the twist of the twisted portion of the bore in the drill steel so that when the upper twisted portion of the adapter engages the drill steel there is a secure attachment therebetween. The angle of twist of the lower twisted portion corresponding to the twist of the twisted portion of the bore in the drill steel so that when the lower twisted portion of the adapter engages the drill steel there is a secure attachment therebetween.
In another form thereof, the invention is an adapter for use in connecting a drill steel that has a substantially straight bore and another component that has a bore with a twisted portion. The adapter comprises an elongate body with opposite ends and a straight portion adjacent the one end thereof and a twisted portion adjacent to the other end of the elongate body. The angle of twist of the twisted portion of the elongate body corresponds to the angle of the central bore of the other component so that when the twisted portion of the adapter engages the other component there is a secure attachment between the adapter and the other component.
In another form thereof the invention is a drill steel that includes an elongate body that has an axially forward end and an axially rearward end. The elongate body contains a longitudinal bore presenting a twisted configuration wherein the twisted configuration exists along substantially the entire length of the longitudinal bore.
In still another form thereof, the invention is a drilling assembly that comprises a cutting bit and a drill steel. The drill steel has an elongate body with an axially forward end and an axially rearward end. The elongate body contains a longitudinal bore that presents a twisted configuration wherein the twisted configuration exists along substantially the entire length of the longitudinal bore. The cutting bit is operatively connected to the axially forward end of the drill steel.